Adding support for mysql error codes

[Ettemlevest]

#437

[avbdr]

can you please update readme as well? thank you

[Ettemlevest]

Thanks for the reminder. I added a small description to the readme.

[avbdr]

as well, I noticed you are not cleaning up errno variable in reset() function. Its getting called after each query execution to remove all the data

[Ettemlevest]

I just added the errno parts after every $_stmtError lines but I did not check to reset the values. In this case we should also reset the $_stmtError string.

[avbdr]

sorry, my bad, this variables shouldnt be reset :) as you are using them after execution
fine. ill land this as is